1. Field of the Invention
The present embodiments relate to an organic light emitting diode display, and more particularly, to an organic light emitting diode display having a thin film encapsulation (TFE) structure.
2. Description of the Related Art
An organic light emitting diode (OLED) display has a plurality of organic light emitting diodes each with a hole injection electrode, an organic emissive layer, and an electron injection electrode. With the organic light emitting diode display, electrons and holes are combined with each other in the organic emissive layer to thereby generate excitons. When the excitons shift from the excited state to the ground state, energy is generated so as to emit light, and images are displayed on the basis of the emitted light.
Accordingly, the organic light emitting diode display involves an emissive or self-luminance characteristic, and differs from a liquid crystal display (LCD) in that it does not require a separate light source such that it has reduced thickness and weight. Furthermore, as the organic light emitting diode display has high quality characteristics such as lower power consumption, high luminance, and short response time, it has been spotlighted as a next generation display device.
However, an organic light emitting diode may be deteriorated due to internal and external factors. With the internal factors, the organic emissive layer is deteriorated under the atmosphere of oxygen from indium tin oxide (ITO) being the electrode material, or under the interfacial reaction between organic layer components of the organic emissive layer. The external factors include external moisture and oxygen, and ultraviolet rays. As the external oxygen and moisture seriously influence the life span of the organic light emitting diode, it is very important to package the organic light emitting diode such that it is sealed from the outside in a vacuum-tight manner.
A thin film encapsulation (TFE) technique may be introduced in packaging the organic light emitting diode. With the thin film encapsulation technique, one or more of inorganic and organic layers are alternately deposited on the organic light emitting diodes formed at the display area of the substrate, thereby covering the display area with a thin film encapsulation layer. With the organic light emitting diode display with such a thin film encapsulation layer, if the substrate comprises a flexible film, it can be bent easily, and is advantageous in forming a slim structure.
As an organic layer (for example, a pixel definition layer) is commonly formed external to the display area with a predetermined width, the thin film encapsulation layer contacts the organic layer at the edge thereof. In this case, the external moisture and oxygen may intrude into the thin film encapsulation layer along the organic layer. Consequently, during the process of driving the organic light emitting diode display, the organic light emitting diodes placed at the edge of the display area are deteriorated so that display failures may occur.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the embodiments and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. The present embodiments overcome the above disadvantages as well as provide additional advantages.